Before hiring from abroad the employer has to get a Labor Certification application approved by the Department of Labor. PERM, Program Electronic Review Management, is a Labor Certification application process that came into effect on March 28, 2005.
card - thin cardboard, usually rectangular. corrugated board, corrugated cardboard - cardboard with corrugations (can be glued to flat cardboard on one or both sides) paperboard, poster board, posterboard - a cardboard suitable for making posters. pasteboard - stiff cardboard made by pasting together layers of paper. strawboard - a coarse yellow cardboard made of straw pulp. paper - a material made of cellulose pulp derived mainly from wood or rags or certain grasses.
It is a light-weight tough material which can easily be cut with a utility knife. Manufacturers typically offer a wide variety of colors and thicknesses (quite commonly 3, 4, 5 mm). Corrugated plastic made of polycarbonate is sometimes referred to as Twinwall plastic. Chemically, the sheet is inert, with a neutral pH factor.